Cleavage of the BRI2 protein within its ectodomain (residue Arg243 and Glu244, KGIQKR↓EAS) by pro-protein convertases (PCs) [7]–[9] releases a 23 amino acid pro-peptide from the wild-type precursor protein and 34 amino acid long amyloid peptides in patients with FBD (ABri) and FDD (ADan) [3], [4]. This evidence concerns the gene ITM2B and ABri amyloidosis.